1. Field of the Invention
The present invention relates to a nonslip member capable of being used as an outsole of shoe and to a manufacturing method of the nonslip member.
2. Prior Art
Hitherto, a nonslip member in which a nonslip convex of polyurethane elastomer is fixed to a soft base fabric such as nonwoven fabric has been known (see, for example, the Japanese Laid-Open Patent Publication (unexamined) Hei 6-826 and the Japanese Laid-Open Patent Publication (unexamined) Hei 6-296502). By using the base fabric, when used as an outsole, such a nonslip member exhibits characteristics of light weight and easy bending, and moreover has various advantages such as freedom in design, improvement in adhesive property to midsole, etc.
An example of conventional manufacturing method of the nonslip member is hereinafter described.
FIG. 9 shows the conventional manufacturing method disclosed in the Japanese Laid-Open Patent Publication (unexamined) Hei 6-826, and in which FIG. 9(a) is a perspective view showing an injection step of urethane resin, FIG. 9(b) is a perspective view showing a squeezing step, FIG. 9(c) is a perspective view showing a heating step, and FIG. 9(d) is a perspective view showing a nonslip member.
As shown in FIG. 9(a), a polyurethane resin U is supplied to a metallic mold 100. Then, as shown in FIG. 9(b), after squeezing an excessive portion of the polyurethane resin U overflowing on the surface of the metallic mold 100 with a jig 101, the polyurethane resin U is heated and aged at 100 for 5 to 15 minutes. Subsequently, as shown in FIG. 9(c), a nonwoven fabric F is placed on the metallic mold 100, a holding plate 102 is further placed thereon, and they are held from above and under for closing, then polyurethane resin U is heated again at 120xc2x0 C. for 30 to 40 minutes and hardened. Thereafter, the polyurethane resin U is released from the metallic mold and heated at 90xc2x0 C. for a long time, then cooled, whereby a nonslip member (outsole) shown in FIG. 9(d) is obtained. Thus, in this prior art, by xe2x80x9csqueezingxe2x80x9d the resin U overflowing on the surface of the metallic mold 100, the surface of the nonwoven fabric is prevented from being stuck by the excessive portion of polyurethane resin U so as not to affect the softness and light weight of the nonwoven fabric F.
However, since the polyurethane elastomer is used in the prior art, the step called xe2x80x9csqueezingxe2x80x9d is essential as mentioned above, and therefore a problem exists in that manufacturing efficiency is lowered. Moreover, a skill is required in the xe2x80x9csqueezingxe2x80x9d step.
Now, another conventional manufacturing method of the nonslip member is hereinafter described.
FIGS. 10(a), (b), (c), (d) and (e) are sectional views showing the conventional manufacturing method in order of the steps thereof disclosed in the Japanese Laid-Open Patent Publication (unexamined) Hei 6-296502.
To manufacture the nonslip member according to this prior art, first as shown in FIG. 10(a), a blank sheet S is inserted between an upper punch die 211 on which a predetermined shape of concave 213 is formed and a lower punch die 212 on which a predetermined shape of convex 221 is formed. Then, by the frictional force between the concave 213 and a convex 221, a small piece 230 is punched out from the blank sheet S. After the punching, by disengaging the dies 211 and 212 as shown in FIG. 10(c), a base 226 on which a base fabric F is placed is disposed under the upper punch die 211 shown in FIG. 10(d). Then, as shown in FIG. 10(e), by moving the upper punch die 211 and the base 226 close to each other, the base fabric F is held therebetween, and by moving a press rod 214 downward, the small piece 230 remaining in the concave 213 is extruded out of the concave 213 to be pressed on the base fabric F.
Thus, in this prior art, it is necessary to operate the press rod 214, after the steps of disengaging the pair of metallic molds 211 and 212 shown in FIG. 10(c), disposing the base 226 shown in FIG. 10(d), and moving the upper punch die 211 downward. As a result, a further problem exists in that manufacturing efficiency is poor.
Accordingly, a primary object of the present invention is to provide a nonslip member and a manufacturing method in which any squeezing step is not required.
Another object of the invention is to provide a manufacturing method of a nonslip member superior in manufacturing efficiency.
To accomplish the foregoing objects, there is provided according to the invention a nonslip member in which a large number of nonslip convexes are fixed to an upper surface of a base fabric performing an anchoring action (generally called xe2x80x9canchoring effectxe2x80x9d), characterized in that the nonslip convexes are composed of a rubber.
In the manufacturing method of a nonslip member according to the invention, first, an unvulcanized rubber is pressed between a metallic mold having a large number of molding concaves corresponding to the nonslip convexes and a holding plate, and the unvulcanized rubber is semi-vulcanized by heating. After the semi-vulcanization, the holding plate is released and burrs not accommodated in the molding concaves of the metallic mold are removed. Thereafter, a base fabric is laid covering a part to be molded serving as the nonslip convexes. By pressurizing and heating the part to be molded while laying the base fabric and closing the metallic molds, the part to be molded is vulcanized, and the vulcanized nonslip convexes are caused to get in the upper surface of the base fabric performing the anchoring action to be fixed thereto.
In the invention, since the nonslip convexes are not composed of resin but of rubber, by semi-vulcanizing the nonslip convexes, burrs not accommodating in the molding concaves are hardened. As a result, the burrs can be removed and, therefore, the conventional xe2x80x9csqueezingxe2x80x9d step is not required at all. Furthermore, by composing the nonslip convexes of rubber, hardness of the nonslip convexes can be reduced and gripping characteristic thereof is improved, and therefore it is difficult for the nonslip member to slip even on the slippery smooth floor or road.
Further, when peripheral edge of each nonslip convex is provided with a thin reinforcing part, anchoring force between the nonslip convexes and the base fabric are increased. Furthermore, when the thin reinforcing part is recessed from the upper surface of the base fabric, there is no possibility of losing the advantage of light weight.
In the invention, the xe2x80x9csemi-vulcanizationxe2x80x9d does not mean that an unvulcanized rubber is vulcanized by half or so, but means that a portion of the unvulcanized rubber supplied to the metallic mold is completely or incompletely vulcanized and the remaining portion is left unvulcanized or incompletely vulcanized. In other words, the xe2x80x9csemi-vulcanizationxe2x80x9d means that a portion to be a burr among the unvulcanized rubber supplied to the metallic mold is completely or incompletely vulcanized and a portion filling up the molding concave among the unvulcanized rubber is left unvulcanized or incompletely vulcanized.
Being different depending upon kind and composition of polymer employed, the semi-vulcanization is usually performed by pressurizing and heating the unvulcanized rubber for about 40 sec to 60 sec while keeping the temperature of the metallic mold and the holding plate at 145xc2x0 C. to 160xc2x0 C. (preferably at 150xc2x0 C. to 155xc2x0 C.). In such a manufacturing method, the xe2x80x9csemivulcanizationxe2x80x9d is an essential requirement because the nonslip convexes are strongly fixed to the base fabric as a result that the molded part is vulcanized after getting in the upper surface of the base fabric performing the anchoring action.
In the invention, the fixation of the rubber forming the nonslip convexes to the base fabric is achieved largely depending on the anchoring action of the upper surface of the base fabric. Accordingly, it is essential that the semi-vulcanized rubber of small fluidity sufficiently gets in very small gaps among the fibers of the base fabric. From such a viewpoint, it is preferable that the principal polymer forming the nonslip convexes is a synthetic rubber of smaller molecular weight than NR (natural rubber). Further, in case of using the nonslip member as shoe sole or the like, it is preferable that BR (butadiene rubber), SBR (styrene-butadiene) or blend of BR and SBR is used as the synthetic rubber.
In the invention, xe2x80x9ccomposed of rubberxe2x80x9d means that a rubber has a rubber component of not less than 50 weight % with respect to the entire polymer. The nonslip convexes may be composed of either a foaming material or a non-foaming material. The xe2x80x9cprincipal polymerxe2x80x9d means a polymer component of not less than 50 weight % with respect to the entire polymer, and it is preferable to blend a synthetic rubber with NR or to blend BR with IR (isoprene rubber). In the invention, it is also preferable to blend the rubber with a resin such as EVA (ethylene-vinyl acetate copolymer), RB (syndiotactic 1,2-polybutadiene) or polyurethane to which a cross linking agent is added.
In addition, the blend ratio of BR to the entire polymer is preferably about 70 to 95 weight % and, more preferably, about 80 to 90 weight %. Polymer of the remaining portion is preferably NR or IR.
In the manufacturing method of the nonslip member according to the invention, a mounting base, a female mold, and a male mold are prepared. The mounting base is used for laying and mounting a base fabric thereon. The female mold is provided with through holes passing through between two faces of the female mold. The male mold has a large number of punching convexes to be engaged with the through holes.
To manufacture the nonslip member, first, a base fabric is laid covering the mounting base so that the base fabric is disposed between the mounting base and one face of the female mold. In the meantime, a plate-like material to be molded is disposed between another face of the female mold and the male mold. After disposing the base fabric and the plate-like material, the male mold and the female mold are engaged with each other, whereby a large number of small pieces coincident to the shape of each through hole is punched out from the plate-like material before each punching convex is completely engaged with each through holes.
After the punching step, the male mold and the female mold are engaged with each other, and each small piece is pressurized and heated between the punching convexes and the mounting base, whereby a polymer forming the small pieces is bridged and fixed to the base fabric to serve as nonslip convexes.
In the invention, the base fabric and the plate-like material to be molded are disposed along the two faces of the female mold having a large number of through holes, a large number of small pieces are punched out from the plate-like material, and the small pieces are molded and fixed to the base fabric by only one engaging motion. As a result, manufacturing efficiency is improved.
As the xe2x80x9cbase fabricxe2x80x9d used in the invention, any material performing the anchoring action for fixing the nonslip convexes (generally called xe2x80x9canchoring effectxe2x80x9d) can be preferably used. For example, a material selected from the group comprising woven fabric, knitted fabric and nonwoven fabric can be used as the base fabric.
As the xe2x80x9cplate-like materialxe2x80x9d, a rubber not bridged, a material composed of a thermoplastic resin forming a principal polymer or a blend of these materials can be used. As the rubber, BR, SBR, NR, IR or a blend of these rubbers can be used. As the thermoplastic resin, EVA(ethylene vinyl acetate copolymer), PE (polyethylene) or a blend of these resins can be used. The nonslip convexes fixed to the base fabric may be either a foaming material or a non-foaming material.
As the shape of the nonslip convexes, various shapes such as cylinder, disk, square can be adopted. In addition, any stepped shape may be adopted. In case of adopting a stepped shape, a molding concave corresponding to the nonslip convex is preliminarily formed at the top end of each punching convex of the male mold, and by pressurizing and heating each punched out small piece between the punching convex and the mounting base at the time of fixing to the base fabric, each small piece is molded into a nonslip convex of a shape coincident to the molding concave.
In the invention, in case of forming the nonslip convexes into a stepped shape, it is preferable that the nonslip convexes are cooled keeping the engagement between the male mold and the female mold, after pressurizing and heating each small piece for the molding and fixation. This is because a shape of the molded nonslip convexes is secured by the cooling and it is easy to get a desired shape.